Watch intake of vitamins, minerals

EATING WELL

April 11, 1995|By Colleen Pierre | Colleen Pierre,Special to The Sun

Just about any time you try to get something for nothing, you're likely to be taken for a ride. Nowhere is that more certain than in the world of vitamin and mineral supplementation, especially when you're talking about stress relief or sports performance.

It's true that "stress" will increase vitamin and mineral needs. But that's physiological stress, like being burned over half your body. Emotional stress has never been shown to increase nutritional needs. So taking a "stress relief" vitamin is no more useful than taking a standard multivitamin tablet that meets 100 percent of the Recommended Dietary Allowance (RDA). But usually it's more expensive.

The sports world, too, is beset by promises of better performance from massive doses of vitamins and minerals. This never proves true.

What we do know is that malnourished athletes will show improvement when their diets are brought up to standard levels. But they get no benefit from doses beyond the RDA. No legally available vitamin, mineral, amino acid or other substance will increase muscle growth or improve athletic performance.

So, the National Council Against Health Fraud has petitioned the Food and Drug Administration to force vitamin manufacturers to tell you the truth.

That means that they will have to stop using false or unproven claims to market sports vitamins and stress formulas.

This is shocking considering those new food labels we've learned to trust. Health claims on food labels are tightly controlled by the FDA. Unfortunately, different laws apply to vitamins.

So, overly enthusiastic claims abound.

Chromium picolinate, for instance, is touted as the quick, easy way to increase muscle mass and strength, as well as burn fat (the all-American come-on). In advertising, it is often compared to anabolic steroids in muscle-building magic. Yet research on its effectiveness is contradictory at best. Even the most favorable studies fall well short of product claims.

There is no RDA for chromium, but the National Academy of Sciences has established 50 to 200 micrograms per day as a safe and effective dose. The way in which chromium works is not known, but it does appear to improve insulin usage.

Studies that appear to demonstrate chromium's usefulness for muscle building are not well controlled. One study published in the International Journal of Sport Nutrition found some muscle-size increase in beginning female body builders supplemented with 200 micrograms per day, but not in males. Those women showed no increase in strength, however, calling the results into question.

In addition, none of the participants was tested for chromium status, either before or after the study. That made it impossible to show that chromium itself was responsible for any observed changes.

Finally, there were no specific training routines used by the participants, making it difficult to tie muscle-building to chromium intake rather than the intensity or regularity of workouts.

A second article, also published in the International Journal of Sport Nutrition, notes that the safety of chromium picolinate has never been documented. The article points out that the element in high doses has been reported to cause physiological disorders by changing gland activity and the shape and function of cells, as well as increasing the loss of trace minerals. In addition, chromium may compete with iron for absorption, so that high doses of chromium over an extended time may produce iron deficiency.

The article also points out that even in chromium-deficient athletes, "large, short-term muscle mass increases would not be expected. Rather, marginal body weight increases, occurring over a relatively long period of time (perhaps months) would be more consistent with the anabolic nature of enhanced insulin function."

Most athletes would do just as well to improve the quality of their diets by eating more close-to-natural foods and fewer highly processed foods and sweets. A standard multivitamin supplement will bring chromium up to standard levels for athletes who fear their eating habits offer too little chromium.

Colleen Pierre, a registered dietitian, is the nutrition consultant at the Union Memorial Sports Medicine Center and Vanderhorst TC Associates in Baltimore.

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